Amorphous WO₃ Films via Chemical Vapor Deposition from Metallorganic Precursors Containing Phosphorus Dopant

Abstract

Amorphous WO3 films, doped with phosphorus, have been synthesized by chemical vapor deposition of volatile, low-melting P-substituted tungsten carbonyls. The presence of a small quantity of dopant released by the precursor during its decomposition is sufficient to inhibit the crystallization of the tungsten oxide on the matrix (P/W 2−4 atom % on Si(100) and ca. 10 atom % on KGlass). The nature of the film is scarcely affected by the experimental conditions of deposition (namely p O 2 partial pressure) and the quantity of the P dopant is properly tuned by an appropriate choice of the molecular precursor, being in the order W(CO)4[P(OEt)3]2 (P/W 1/1) > W2(μ-PR2)2(CO)8 (P/W 1/4) > W(CO)4(PEt3)2 (P/W 1/10 on KGlass, 1/30 on Si). The films on KGlass exhibit interesting electrochromic properties with a maximum efficiency of 66 cm2/C.

Amorphous WO3 Films via “Wet” CVD of a WVI Oxoalkoxide Precursor

“…940 cm ±1 , and becomes slightly sharper after thermal treatment of the films. In contrast to analogous spectra obtained from polycrystalline samples grown from W(CO) 6 , [10] all the samples appear to be amorphous, irrespective of the temperature of the post- deposition treatment. This fact is confirmed by diffractometric analysis.…”

“…[9] We have recently reported that good quality amorphous WO 3 films can be obtained by CVD from metal±organic precursors containing a phosphorous dopant, such as W 2 -(l-PR 2 ) 2 (CO) 8 (R = Me, Et), trans-and cis-W(CO) 4 -(PEt 3 ) 2 , and trans-W(CO) 4 [P(OEt) 3 ] 2 . [10] In that case it was possible to grow amorphous films at high temperatures by taking advantage of the ability of oxidized phosphorous derivatives to vitrify the host matrix. [11] In this paper, we suggest an alternative synthetic route using an oxoalkoxide of W VI (the tetra-tert-butoxide derivative WO(O t Bu) 4 ) as the CVD precursor.…”

Multistage Coloring Electrochromic Device Based on TiO2 Nanotube Arrays Modified with WO3 Nanoparticles

“…Therefore, nanoparticulate or nanoporous films are usually desired. Normally, the approaches for producing large surface area electrodes include sol–gel deposition,7 sintering nanoparticles,8 chemical vapor deposition9 and electrodeposition 10. Among various methods for the synthesis of nano‐structures, the fabrication of self‐organized oxide nanotube (NT) arrays by a simple but optimized electrochemical anodization of a metal substrate represents a most elegant and economic approach 11.…”

Synthesis and electrochemical capacitance of long tungsten oxide nanorod arrays grown vertically on substrate

“…Thin films and nanostructures of tungsten oxides have been fabricated by thermal evaporation [6], vapor-solid growth [7], chemical vapor deposition [8], hydrothermal synthesis [9], sol-gel process [10], solvothermal process [11], electrodeposition [12], and electrochemical anodization [13]. Recently, the anodization process using an anodic aluminum oxide (AAO) mask was used to produce tungsten oxide nanorods with good vertical alignment on a substrate [14].…”